Heat pipe and manufacturing method for the same

ABSTRACT

A heat pipe containing a sintered powder wick and a corresponding manufacturing method improves the capillarity action of the heat pipe. Through sintering copper powder onto the surface of a copper wick, an evenly sintered result can be obtained. Then, the wick with sintered surface is placed into a hollow copper pipe to provide sufficient capillary force to a working fluid.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a division of U.S. patent application Ser. No. 11/163,475, filed Oct. 20, 2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heat pipe, and more specifically, to a heat pipe containing a sintered powder wick and manufacturing method for the same.

2. Description of the Prior Art

Since many electronic information products have evolved to be lighter, smaller, and with more functions, the working frequency of electronic elements rises correspondingly. High power consumption and heat production are accompanying problems. Since cooling elements are becoming more important, the cooling efficiency of cooling elements needs to be raised. Besides taking metals having high thermal conducting efficiency like copper or aluminum as thermal conductors and using cooling fans to improve air convection, heat pipes are becoming more widely applied to cool information products.

A heat pipe works by dissipating latent heat generated when a working fluid undergoes a phase change. The heat conductivity of a typical heat pipe is about ten to a hundred times that of plain materials with high thermal conducting efficiency, such as copper. A heat pipe can effectively solve a heat problem in a small space and also has the advantages of noiselessness and low power consumption. Typical heat pipes can be categorized as groove, sintered powder, mesh, fiber, and hybrid. Each structure has its advantages and disadvantages. For example, the groove heat pipe has a relatively large heat transferring ability but poor capillary effect; the capillary effect of a mesh heat pipe is degraded in the bent part of the pipe, as is that of the fiber heat pipe since the density of the fibers in the bent part differs.

As to the better capillary action of a sintered heat pipe to that of other types of heat pipes, please refer to FIG. 1, which is an illustration of a conventional sintered heat pipe 10. The heat pipe 10 comprises a hollow metallic pipe 20, metallic sintering powder 30, and a working fluid 40 that fills the hollow center of the hollow metallic pipe 20. Generally the material of the hollow metallic pipe 20 and the metallic sintering powder 30 is copper, which has high heat conductivity, and the heat pipe 10 uses water or alcohol as the working fluid 40. The two ends 22, 24 of the heat pipe 10 are sealed, wherein the first end 22 is a heat source end that connects to an external heat source (such as a chip or a CPU) and the second end 24 is a heat sink end that connects to a cooling device (not shown in the figure) to dissipate heat. The cooling device can be heat sink with fins that provides natural air convection or cooling fan that forces air convection.

Please refer to FIG. 2 for a flow chart of manufacturing a conventional sintered heat pipe. The manufacturing of the heat pipe comprises:

Step S100: dispose a metallic catalytic stick (generally a stainless steel stick or an aluminum stick) in a hollow copper pipe that is to be sintered;

Step S110: fill copper powder into space between the hollow copper pipe and the metallic catalytic stick and heat the powder; with catalytic action of the catalytic stick, the copper powder is sintered to cover the inner wall of the hollow copper pipe and the catalytic stick is removed after the sintering is finished;

Step S120: vacuate the sintered copper pipe and add a working fluid;

Step S130: seal the two ends of the copper pipe and connect the two ends of the copper pipe to a heat source and a heat sink respectively.

As Step S110 shows, the manufacturing process of a conventional sintered heat pipe uses an aluminum stick as a catalyst that can sinter copper powder onto the inner wall of the copper pipe. Since the sintering process is not easy to control, the distribution of the sintered powder is likely to be uneven. This seriously lowers the efficiency of the conventional sintered heat pipe.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide a heat pipe containing a sintered powder wick and manufacturing method for the same to solve the above problem.

The heat pipe in the present invention, includes a metallic pipe; and a wick disposed in the metallic pipe and covered with sintered powder.

Another object of the present invention is to provide a method for manufacturing a heat pipe containing a sintered powder wick. The method in the present invention includes steps of sintering copper powder to cover a surface of a wick, placing the wick covered with the sintered copper powder in a metallic pipe, and sealing the two ends of the metallic pipe.

These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a conventional sintered heat pipe.

FIG. 2 is a flow chart of manufacturing the conventional sintered heat pipe in FIG. 1.

FIG. 3 is an illustration of a present invention heat pipe containing a sintered powder wick.

FIG. 4 is an illustration of another exemplary embodiment of the present invention.

FIG. 5 is a manufacturing flow chart of the heat pipe in FIG. 3.

FIG. 6 is an illustration of manufacturing the sintered powder wick of the manufacturing method.

DETAILED DESCRIPTION

FIG. 3 shows a heat pipe 100 of an illustration of the present invention. The heat pipe 100 contains a sintered powder. The heat pipe 100 includes a metallic pipe 120 and a wick 130. The metallic pipe 120 is a hollow copper pipe having a heat source end 122 and a heat sink end 124. The inner wall of the metallic pipe 120 can be smooth or sintered. The metallic pipe 120 contains a working fluid for absorbing heat from the heat source end 122 and dissipating heat at the heat sink end 124. The working fluid is also capable of returning to the heat source end 122 by a capillary force provided inside the metallic pipe 120. The wick 130 is a copper stick covered with sintered powder 132 on its surface. The wick 130 is disposed in the metallic pipe 120. Generally, the inner wall of the metallic pipe 120 of the heat pipe 110 is smooth and needs no further surface processing. The capillary force that drives the working fluid back to the heat source end 122 is provided by the sintered surface of the wick 130. When the inner wall of the metallic pipe 120 is covered with sintered powder 132 like a conventional sintered heat pipe, the further disposition of the wick 130 into the hollow center 140 will improve capillarity action of the heat pipe 110.

The two ends 122, 124 of the heat pipe 110 in FIG. 3 and the corresponding connections to a heat source and a heat sink are not shown in FIG. 3 for simplicity of illustration. Nevertheless, the two end 122, 124 of the heat pipe 110 are actually sealed, wherein the heat source end 122 is connected to an external heat source (such as a chip or a CPU) and the heat sink end 124 is connected to a cooling device for dissipating heat.

Please refer to FIG. 4. To increase the capillary action capability of a heat pipe 210, the heat pipe 210 containing a sintered powder wick of the present invention can use a copper stick having a bundle of metallic fibers (such as a bundle of copper fibers) as a wick 230. That is, the wick 130 of the heat pipe 110 in FIG. 3 is substituted by the metallic fiber bundle 230 of the heat pipe 210. The metallic fiber bundle 230 is composed of a plurality of metallic fibers 232. Different from a conventional fiber-bundle heat pipe, the plurality of metallic fibers 232 of the metallic fiber bundle 230 has metallic sintered powder 234 on the surface that can strengthen the capillary force which is inherently weak at a bent part of the conventional fiber-bundle heat pipe. Copper powders are a good choice for the material of the sintered powder 132, 234 since copper has high potential for transferring heat.

Please refer to FIG. 5. The present invention provides a new method for manufacturing a heat pipe containing a sintered powder wick. As FIG. 5 shows, the manufacturing method for the present invention comprises:

Step S200: sinter copper powder to cover a surface of a wick;

Step S210: dispose the wick covered with the sintered copper powder in a metallic pipe;

Step S220: vacuate the metallic pipe containing the wick;

Step S230: add a working fluid into the metallic pipe;

Step S240: seal the two ends of the metallic pipe;

Step S250: change the shape of the metallic pipe.

Please refer to FIG. 6. Different from the conventional technique, the technique of the present invention emphasizes placing a sintered copper wick covered with the sintered copper powder in the heat pipe to improve the capillary force on the working fluid. In Step S200, a metallic catalytic container 150 (generally a stainless steel or aluminum container), filled with sintering powder 134 (copper powder) that is to be sintered to cover the surface of the wick 130, contains the wick 130. Then, the wick 130 along with the sintering powder 134 is heated to a certain temperature. By the metallic catalytic container's 150 catalytic effect, the sintering powder 134 adheres to the surface of the wick 130. Since the manufacturing method of the present invention sinters the sintering powder 134 to cover an outer surface of the wick 130, the sintering process can be monitored precisely, and through rotating the wick 130 during the sintering process, the sintering powder 134 can be evenly sintered to cover the surface of the wick 130. This increases the quality of sintering. The present invention manufacturing method can prevent the problem of unevenly sintered powder, which reduces the efficiency of the heat pipe and can even fall off the inner wall of the heat pipe.

In addition, the shape of the heat pipe can be changed to apply the heat pipe of the present invention to various situations, as in Step S250. Generally, changing the shape of the heat pipe includes pressing and extruding the heat pipe where the shape is selected from a group consisting of pressing and extruding the metallic pipe, and folding the heat pipe. Step S250 further comprises changing the shape of the metallic pipe to form a drop height of the shape of the metallic pipe.

The manufacturing method of the present invention sinters a metallic powder to cover an outer surface of a wick to obtain an evenly sintered result. By the sintered surface of the wick, which is disposed in a hollow copper pipe, the capillary force can sufficiently drive the working fluid back to the heat source end. In such way, the efficiency of the sintered heat pipe can be remarkably improved compared with the conventional sintered heat pipe.

Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims. 

1. A method for manufacturing a heat pipe containing a sintered powder wick, comprising: sintering copper powder to cover a surface of a wick utilizing a sintering process, the wick being rotated during the sintering process; placing the wick covered with the sintered copper powder in a metallic pipe; and sealing the two ends of the metallic pipe.
 2. The method of claim 1 further comprising vacuating the metallic pipe containing the wick.
 3. The method of claim 1 further comprising adding a working fluid into the metallic pipe.
 4. The method of claim 1 wherein sintering the copper powder comprises: placing the wick in a container filled with copper powder; and sintering the copper powder to cover an outside surface of the wick.
 5. The method of claim 1 further comprising changing the shape of the metallic pipe after sealing the two ends of the metallic pipe.
 6. The method of claim 5 wherein the step of changing the shape of the metallic pipe is selected from a group consisting of pressing and extruding the metallic pipe.
 7. The method of claim 5 wherein changing the shape of the metallic pipe comprises folding the metallic pipe.
 8. The method of claim 5 further comprising changing the shape of the metallic pipe to form a drop height of the shape of the metallic pipe. 